After textile fibers, filaments and the like are treated in a loose state or as wads or in a mat or web of nonwoven fibers by a treating liquid, it is generally desirable to remove the treating liquid, i.e. to extract the liquid from the fibers for the drying thereof. Generally the textile material contains several times its weight of the treatment liquid and hence the means necessary to dehydrate the textile material, i.e. remove the water or other liquid therefrom, may be somewhat complex.
For example, because of the large volume and weight of treating liquid entrained with the textile material from the treatment vessel, it is not possible to simply subject the textile material to an elevated temperature for a prolonged period because the treatment period becomes prohibitive and the transport path over which the material must be subjected to the drying process becomes inordinately long to accommodate such techniques in conventional textile mills and the like. In fact, the mere use of long transport paths for conveying textile materials through a heated zone has been found to be impractical and even impossible in the case of wads or free textile fibers.
The dehydration or drying of such textile materials can, however, be carried out by continuous centrifugal extraction, e.g. using an extractor of the type described in French Pat. No. 2,087,221 issued May 12, 1970.
This extractor comprises a charging hopper or feeder from which the textile material is introduced into the centrifugal extractor, a distribution cone onto which the material is deposited, a perforated basket receiving the material from the distribution cone, and a pushing plate received at the bottom of the basket and adapted to be displaced axially for driving the extracted material toward the free edge of the basket, the entire assembly being received in the center of a fixed tub, vat or housing.
According to an important feature of this type of centrifugal extractor, the housing has an orifice located at the level of the free edge of the basket and from which the extracted material can be expelled tangentially. The free edge of the basket is provided with vanes or blades adapted to project the extracted material in a tangential manner mentioned above and simultaneously to create a displacement of air to form a transport medium whereby the textile material is conveyed to a conduit by pneumatic emtrainment.
Generally the conduit through which the textile material is pneumatically entrained empties into the workroom or into a chamber of large dimensions in which the transport fluid (usually air) and the extracted material can be separated.
This chamber of large dimension is at the elevated pressure induced by the pneumatic transport system. This elevated pressure makes it difficult to recover the textile materials from the chamber. Furthermore, because of the size of the chamber which has hitherto been deemed necessary, it is difficult to carry out the total cleaning of the chamber which is customarily necessary when one material is to be changed over for another having different characteristics. In practice such cleaning has been found to require an extraordinarily long operation and is difficult to achieve from the point of view of completeness.